The present invention relates to a control device and a control method for controlling carriers in a machine, in particular, to continuously move carriers from a first to a second conveying device.
In machines for producing an article, conveying systems are used to convey parts, tools, etc., which are usable for the production of the article, to different stations of the machine. Such a machine is described, for example, in US 2004/0049308 A1 which discloses an assembly for processing substrates, in which a conveying device for moving the substrates from a vacuum lock to a process chamber is provided.
In such machines for producing an article, carriers are conveyable by the use of magnetic force. The magnetic force can be produced by coils fixedly arranged in one or more tracks along which the carriers travel. Therewith, it is possible to convey each carrier with a velocity specific to the single carrier. However, the cost of such a system is higher than the cost of systems, where the carriers are all moved with the same velocity.
Therefore, it is desirable that carriers are only moved by magnetic force in case different velocities of the carriers are needed. In other areas of the machine, conveying devices like transport belts conveying all carriers with the same velocity could be used instead of a conveying device making use of magnetic force.
Presently, the combination of a transport belt conveying all carriers with the same velocity and a conveying device using magnetic force has the disadvantage that a carrier can only be moved from the conveying device using magnetic force to a conventional device, like a transport belt, etc., by standing still. Such stopping of the carrier is undesirable, since the carrier already moved before must again be accelerated starting from its standstill. As a result, the stopping of the carriers lengthens the production process and blasts a lot of energy. These effects are to be avoided as regards the production costs of the machine and environmental aspects.
Therefore, it is an object of the present invention to provide a control device and a control method for controlling carriers in a machine, with which device and method the above-mentioned problems can be solved. In particular, a control device and a control method for controlling carriers in a machine are to be provided with which more flexibility in choosing transport systems within one machine is created without increasing the costs for the machine as regards its production, operation and maintenance.